Such a device and such a process are known from US 2003/0005696 A1. The coolant, particularly water, is heated from 71° C. to 79° C. in an internal combustion engine and then evaporated by means of nozzles. The coolant is then introduced into an evaporating chamber, in which a vacuum of 0.5 bar prevails. The steam is drawn off from this evaporating chamber by means of a pump and afterheated in a exhaust gas heat exchanger. The steam thus afterheated is first introduced into a first turbine, which drives the pump, and it is sent to the working turbine proper only thereafter.
Consequently, the steam generated at first is still subjected to afterheating and secondary compression. Wet steam is obviously formed in such a case in the evaporating chamber (4), because the steam is present within this evaporating chamber together with the cooling water flowing back from the condenser. Therefore, there is a risk during the secondary compression of the wet steam by the pump that the steam will condense again. Moreover, a steam must be delivered, which is associated with higher losses, because, unlike a liquid, steam is a compressible medium. Not only because of this, a large part of the energy of expansion released during the evaporation of the coolant is destroyed by the aftertreatment of the steam.
It known from WO 2004/044386 A2 to feed the coolant, for example, from an internal combustion engine to heat exchanger/evaporator, in which another liquid is heated and evaporated in the process. This evaporated liquid is sent to a turbine and the latter is driven as a result. The turbine drives, in turn, a generator. As is usual in cycles, the steam is subsequently condensed and sent again to the heat exchanger/evaporator by means of a pump.
The drawback of this procedure is that heat losses occur due to the additional heat exchanger. In addition, the liquid or the steam can be heated in the evaporator to a temperature below the temperature of the coolant only. The efficiency is reduced hereby as well. Furthermore, a design effort and maintenance effort are needed for a second system.